Reproductive Activities of Rosy Finches, with Special Reference to Montana

Abstract

The nesting behavior of the gray-crowned rosy finch (Leucosticte tephrocotls tephrocotis) was studied at Logan Pass, Glacier National Park, northwestern Montana, from June to Sept. for 4 years. Seven nests were located in sites in cliffs offering protection from falling rock and from rodent predation. Nests contained 3-5 young, 4 being most common. Additionally, examination of over 400 references dealing with 7 North American races indicates that, of 139 nests, 81% were on cliffs, 14% on the ground, and 5% in old buildings. These data were inadequate to reveal significant differences between races, but clutch size does seem to be significantly larger in the northern races, as a group, than in the southern ones. The male defends a territory around the female until midway in the nestling period when it shifts some of its attention from defense of females to defense of the nest with active young and this may be correlated with the onset of feeding of the young by the male. A roosting perch near the nest may be occupied by the male bird. The rate of feeding at the nest was found to decrease toward the end of the nestling period. Fecal sac removal by an adult is not conditioned by observation of defecation by the young. Adults and young move up from the breeding grounds to the mountain tops late in Aug., and return to the meadows near the nest sites only during storms. Site records indicate a sex ratio near 4 males to 1 female.